The original adaptation of the screenplay for Walt Disney Pictures was written by Jeffrey Boam, who made changes to the novel including given the giant shark wings and having it growl repeatedly at characters.
Screenwriter Shane Salerno's 2004 draft added massive action sequences to the film, including a 65-foot Megalodon shark being attacked by giant Humboldt squid, and the Megalodon shark attacking a group of Orca Whales off the coast of Seattle. These changes pushed the proposed budget of $100 million to over $157 million and cuts were ordered.
One-time-attached director Jan de Bont still keeps a Megalodon tooth and 4-foot model of the Megalodon shark proposed for the film in his office.
Guillermo del Toro was attached to the project at the same time he was circling a remake of "Creature From The Black Lagoon," stating - "There's something about prehistoric fish that are terrifying! Really scary stuff. We don't know everything that used to be down there..."
The film has been in development for 12 years, starting with Walt Disney Pictures, moving to New Line Cinema, where it stayed until the rights to the film expired and New Line was absorbed by Time Warner.
Since the release of 'MEG' the novel, many low-budget Megalodon-themed films have been produced, including 'Shark Hunter', 'Megalodon', 'Shark Attack 3: Megalodon', and 'Haif Mallorca'. None credit original author Steve Alten for his obvious influence and ideas even though the plot lines are extremely similar to his "MEG" book series.
The original title of the novel was "White Death".
There are four novels in the "MEG" series, all featuring the titular title monster, as well as other prehistoric sea monsters that surface to do battle: "MEG," "The Trench," "MEG: Primal Waters," and the soon-to-be-released "MEG 4: Hell's Aquarium" (May 9, 2009).
Screenwriter Shane Salerno was said to have completed 6 drafts of the screenplay based upon notes by New Line Cinema.
The Megalodon shark is the largest carnivorous shark to have ever lived - with a dorsal fin exceeding six feet tall, Megalodons reached lengths of up to 80 feet.